Method of making firearms having interchangeable barrels

ABSTRACT

A firearm having interchangeable barrels wherein each barrel is attached to the receiver portion of the firearm and is prevented from relative rotation with respect thereto by a locking sleeve which fits over the barrel. The barrel is screwed into a threaded bore in the receiver of the firearm until its end face abuts a seating surface therein. The sleeve is then fitted over the barrel and screwed into the same bore in the receiver as the barrel until its end abuts the threaded portion of the barrel. Any tendency of the barrel to rotate out of the receiver is effectively prevented by the locking action of the sleeve.

United States Patent 11 1 Quinney 1 1 Jan. 9, 1973 [73] Assignee: Idaho Bank of Commerce, Rexbur'g,

Idaho [22] Filed: July 16, 1971 [21] Appl. No.2 163,215

Related Application Data [62] Division of Ser. No. 885,382, Dec. 15, 1969, Pat. No.

52 0.5.01 .Q. ..29/1.1 51 1m.c1. ..B23p13/00 [58] FieldofSearch ..29/1.1;42/75 13,77

[56] References Cited UNITED STATES PATENTS 2,216,022 9/1940 Pomeroy ..42/75 B 3,351,994 11/1967 Weller ..2'9/1.1

Primary Examiner-Frank T. Yost Attorney-Stevens, Davis, Miller & Mosher [57] ABSTRACT A firearm having interchangeable barrels wherein each barrel is attached to the receiver portion of the firearm and is prevented from relative rotation with respect thereto by a locking sleeve which fits over the barrel. The barrel is screwed into a threaded bore in the receiver of the firearm until its end face abuts a seating surface therein. The sleeve is then fitted over the barrel and screwed into the same bore in the receiver as the barrel until its end abuts the threaded portion of the barrel. Any tendency of the barrel to rotate out of the receiver is effectively prevented by the locking action of the sleeve.

1 Claim, 3 Drawing Figures PATENTEDJM 9mm 3.708.841

SHEET 2 UF 2 INVENTOR 14/1465 1 Qu/A/A/EY BY MMMQJ/ 75W ATTORNEYS METHOD OF MAKING FIREARMS HAVING INTERCHANGEABLE BARRELS This application is a division of copending application Ser. No. 885,382, filed Dec. 15, 1969, now US. Pat. No. 3,611,611.

This invention relates to firearms in general, and,- mo're particularly, to the provision of a firearm having interchangeable barrels of different caliber.

Although such firearms are known, they have possessed to date numerous disadvantages. Among these is complication of assembly and disassembly when interchanging barrels, and a tendency of the barrels to rotate with respect .to the receiver portion of the firearm when the firearm is fired. In addition, it was extremely difficult, if not impossible, in many such firearms to obtain proper headspacing without the use of gauges, a practice which is quite time-consuming.

Accordingly, it is an object of the present invention to provide a firearm having interchangeable barrels in which the barrels can be changed with ease, and which provides means for positively preventing relative rotation between the barrel and the receiver during firing.

It is a further object of the present invention to provide means in a firearm whereby headspace is automatically determined, and headspace increase caused by erosion in the chamber area of the barrel may be, to a certain extent, easily compensated for.

It is another object of this invention to provide a cylindrical sleeve adapted to slide over the barrel and screw into the same bore in the receiver as the barrel to lock the barrel threads and thus prevent relative rotation between the barrel and the receiver.

It is a further object of the invention to provide barrels of several different calibers for a single firearm, which vary only a small amount in weight so that no matter which caliber barrel one uses, a firearm of approximately the same weight is obtained I Other objects and advantages of the invention will become apparent from the following description and accompanying drawings in which:

FIG. 1 is a fragmentary side elevational view, in vertical section, of a firearm utilizing the sleeve assembly of the present invention;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1 and including a fragmentary side elevation of a spanner wrench for applying and removing the sleeve ofthe present invention; and

FIG. 3 is an exploded perspective view of a barrel and sleeve constructed according to the present invention.

Referring now to FIG. 1, there is shown the action of a firearm embodying the present invention. Receiver portion 11 has concentric bore 12 therein, said bore being threaded at 13 from end face 14 nearly to the annular seating surface 15 at the inner end of the bore. A relieved portion 40 is left at the end of the internal threads 13. Barrel 16 is provided with raised threads 17 at end 18 thereof. (See FIG. 3). These threads are adapted to screw into threads 13 of bore 12 until end face 19 of barrel l6 abuts against seating surface 15. Note from FIG. 1 that threads 17 of barrel 16 are adapted to extend for only a portion of the length of bore 12 when the barrel is attached to the receiver.

(This distance is preferably a little more than one-half the length of bore 12.) Note further from FIG. 1 that shoulder 20 of threads 17 is faced perfectly square,

producing a partialthread thereon at 21. Sleeve 22 is formed with a cylindrical bore 23 therein large enough to allow the, sleeve to slide on barrel 16. At one end thereof, is provided threaded portion 24 which is adapted to be screwed into threads 13 of bore 12. The end face 25 of threaded portion 24 is faced perfectly square, producing another partial thread. Preferably, the threads in threaded portion 24 of barrel sleeve 22 are undercut to provide clearance (not shown in the drawings). Adjacent to threaded portion 24 is a shoulder 26, said shoulder being so positioned with respect to end face 25 as to be spaced a short distance away from end face 14 of receiver 11 when, upon assembly, end face 25 abuts against end face 20 of the barrel. In order to provide a sleek appearance, the exterior surface of barrel sleeve 22 may be tapered from shoulder 26 to end 27 as is shown in FIGS. 1 and 3.

In the embodiment of the invention shown in FIG. 1,

I seating surface 15 of bore 12 is so spaced with respect to firing pin assembly 29 as to provide proper headspacing between end 31 of cartridge 30 and shoulder 32 of barrel firingchamber 33. I

A barrel of the present invention may be inserted as follows:

-First, barrel 16 is screwed tightly into receiver 11 until the end thereof abuts against seating surface 16;

Sleeve 22 is then placed over the barrel and slid rcarwardly until the threaded portion 24 thereof abuts end face 14 of receiver 11. The threaded portion 24 is then screwed into bore 12 until the flat half-threaded surface 20 of the barrel abuts the fiat half-threaded surface 25 ofbarrel sleeve 22. As shown in FIG. 2, spanner wrench 35 is inserted into slot 28 of barrel sleeve 22 and turned in the clockwise direction to tighten the same. Thus, due to the critical positioning of seating surface 15 with respect to firing pin assembly 29, proper headspacing is provided, and due to the fact that interaction between the half thread on the barrel and the half thread on the sleeve forms a locking effect, it is impossible for the barrel to rotate relative to receiver 11 when a cartridge is fired; and thus barrel 16 ,cannot loosen when shooting.

As an additional feature, the construction of the instant firearm is such that as firing chamber 33 is lengthened due to erosion therein, thus increasing the headspace, wear occurs between end face 19 and seating surface 15 due to friction therebetween during barrel interchange. Thus, while chamber 33 is lengthened through erosion, the threaded portion of the barrel is shortened due to wear, causing the barrel to screw in farther. Due to the spacing originally existing between end face 14 and shoulder 26 of sleeve 22, the sleeve is also capable of screwing farther into bore 12 as the aforesaid wear occurs. Normally, when 40-41 chromemolydenum metal is used to form the barrel and receiver portions, 21' space of 10/1000 of an inch between shoulder 26 and end face 14 in a newly manufactured firearm will suffice to assure adequate provision for wear throughout its lifetime. From this, it can be seen that at least in cases where barrels are interchanged regularly, a degree of compensation for.

erosion in the firing chamber is provided, virtually assuring that the gun may be used for long periods of time without'the necessity of returning the same to a gunsmith for headspace adjustment.

- In order to disassemble the barrel from the receiver, spanner wrench 35 is placed in slot 28 of barrel sleeve 22, and is rotated in the counterclockwise direction to loosen the sleeve. The sleeve is then rotated out and slipped off the barrel. Subsequently, the barrel is unscrewed from the bore of receiver 11, and a barrel of a different caliber may then be inserted. All barrels for the gun are manufactured to the same exterior dimensions at the threaded end thereof so that, in practice, only one barrel sleeve and one receiver need be used, without the necessity of using adaptors of any form. Further, the barrels are so designed as to be within two ounces in weight of each other no matter which caliber is being used so that one can shoot the same weight of gun, the same stock, same action, and same scope regardless of caliber be it 22-250 or 30-06.

This invention also contemplates converting a firearm having only one barrel into one which is adaptable for use with interchangeable barrels. This conversion can, of course, only be used on a firearm having the barrel threaded into the receiver. To accomplish the conversion, the present barrel is first removed and the end of the barrel, outside the chambered area, is turned down to a diameter slightly less than the rootto-root diameter of the threads in the end of the barrel. At the same time or in a subsequent operation, part of the length of the existing threads is removed thus leaving a raised threaded portion. The length of the remaining threads is such that when the barrel is screwed into the receiver, at least two completed threads will be left in the receiver in order to engage threads in the sleeve to be fitted. During this turning operation, care is taken to leave a square finish edge on the forward part of the remaining threads.

A sleeve is then made from the same type of material as the barrel, this sleeve being of the general shape previously describedand with threads which are of 'the same diameter and pitch as the threads on the barrel. This sleeve is then placed over the barrel and screwed in place in the same manner as previously described.

Having thus described my invention, 1 claim:

1. The method of converting a firearm having a single barrel threaded into a bore of a receiver to one having interchangeable barrels, comprising the steps of:

a. turning down outside its chambered end, a first barrel adapted to fit said receiver to a diameter less than the root-to-root thread diameter but leaving at least some of the threaded portion intact;

b. removing enough of said threads so that the remaining length of the threaded area is less than the depth of said threaded bore;

. fitting an annular sleeve over the turned down portion of said barrel, said sleeve having threads to screw into said receiver bore and being of a length at least as great as the barrel thread previously removed;

. fitting a second barrel, preferably of different caliber, to said receiver in a similar manner to be locked in place with said annular sleeve; 

1. The method of converting a firearm having a single barrel threaded into a bore of a receiver to one having interchangeable barrels, comprising the steps of: a. turning down outside its chambered end, a first barrel adapted to fit said receiver to a diameter less than the rootto-root thread diameter but leaving at least some of the threaded portion intact; b. removing enough of said threads so that the remaining length of the threaded area is less than the depth of said threaded bore; c. fitting an annular sleeve over the turned down portion of said barrel, said sleeve having threads to screw into said receiver bore and being of a length at least as great as the barrel thread previously removed; d. fitting a second barrel, preferably of different caliber, to said receiver in a similar manner to be locked in place with said annular sleeve. 